A lighting device of this type has a plurality of semiconductor light sources, which can be embodied for example by an LED or a multichip LED module. Said semiconductor light source is usually arranged on a carrier material—called substrate hereinafter—which consists of ceramic. The arrangement including substrate and semiconductor light source is brought into contact thermally with a heat sink, such that the heat that arises during the operation of a semiconductor light source can be dissipated in order to prevent the LEDs from overheating. The use of ceramic as substrate material has the advantage, inter alia, that the electronics of the luminaire are electrically isolated from the heat sink, thereby satisfying the requirements of the respective protection classes. In accordance with these requirements, the LED lighting devices have to be electrically insulated from the heat sink and air clearances and creepage paths between LED luminaire and heat sink have to be taken into account for this purpose. What is problematic here is that as a result of these measures the thermal linking of the semiconductor light source is impaired and the service life thereof is thus reduced.
Semiconductor light sources are often also used for achieving standard-conforming electrical insulation with complex SELV operating devices, which require a very large amount of space in order to comply with the necessary air clearances and creepage paths.
Lamps or luminaires can be subsumed under the term “lighting device”. In this regard, by way of example, OSRAM GmbH sells so-called LED retrofit tubes under the designation SubstiTUBE, which can be used as a replacement for conventional fluorescent lamps in luminaires, without necessitating a conversion of the luminaire. In the case of tubes of this type, a multiplicity of semiconductor light sources are arranged on the large-area substrate, which is very long in accordance with the tube shape. Both during production and in the installed state, these ceramic substrates can break in the event of slight bending of the luminaire. Furthermore, the ceramic materials required for producing such substrates are relatively expensive, and so the lamp price is determined not inconsiderably by the proportion of ceramic.
In conventional luminaires, too, such as are described for example in document DE 10 2008 039 364 A1, the semiconductor light sources are arranged on a ceramic substrate which is configured likewise with a large area or in very complex forms, depending on the geometry of the luminaire, with the result that the same problems as with the tubes occur.